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INSTALLATION INSTRUCTIONS MANUAL
36" Wood Burning Fireplaces
P/N 700,033M, REV. C, 12/2006
Model CST38MH
Retain These Instructions
For Future Reference
Report No. 116-F-20-4
This installation manual will enable you to obtain a safe, efcient and dependable installation of
your replace system. Please read and understand these instructions before beginning your
installation.
Do not alter or modify the replace or its components under any circumstances. Any
modication or alteration of the replace system, including but not limited to the
replace, chimney components and accessories, may void the warranty, listings
and approvals of this system and could result in an unsafe and potentially
dangerous installation.
IMPORTANT! TO ASSURE PROPER ALIGNMENT OF
GLASS DOORS: INSTALL THIS FIREPLACE IN A
SQUARE AND PLUMB CONDITION, USING
SHIMS AS NECESSARY AT SIDES AND/OR
BOTTOM.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
2
1. Before starting your fireplace installation,
read these installation instructions carefully
to be sure you understand them completely
and in entirety. Failure to follow them could
cause a fireplace malfunction resulting in
serious injury and/or property damage.
2. Always check your local building codes.
The installation must comply with all lo-
cal, regional, state and national codes and
regulations.
3. These fireplaces must be installed with
Security Chimneys FTF8 (8" inside diameter)
Chimney System only. These systems are
intended for use in any application where
a traditional masonry type fireplace would
apply. The chimney system must always
vent to the outside of the building.
4. To ensure a safe fireplace system and to
prevent the build-up of soot and creosote,
inspect and clean the fireplace and chimney
prior to use and periodically during the heat-
ing season.
5. Burn approved fuels only as defined in the
Homeowner's Care and Operation Manual.
6. DO NOT use charcoal or coal under any
circumstances.
7. NEVER use gasoline, gasoline-type lantern
fuel, kerosene, charcoal lighter fluid, or
similar liquids to start or “freshen up” a fire
in this fireplace. Keep any flammable liquids
a safe distance from the fireplace.
8. NEVER leave children unattended when there
is a fire burning in the fireplace.
9. Always keep flue damper open when heat is
present in the fireplace.
10. Before servicing, allow the fireplace to cool.
Always shut off any electricity or gas to the
fireplace while working on it. This will prevent
any possible electrical shock or burns.
11. This fireplace is not intended to heat an
entire home or be used as a primary heat
source. It is designed to ensure homeowner
comfort by providing supplemental heat to
the room.
12. Always ensure that an adequate supply
of replacement combustion air from the
outside of the house is accessible to the fire
to support normal combustion. Fireplaces
consume large volumes of air during the
normal combustion process.
• In the event the home is tightly sealed with
modern energy efficient features, the com-
bustion air kit (provided) may not provide
all the air required to support combustion.
• The manufacturer is not responsible for any
smoking or related problems that may result
from the lack of adequate combustion air. It
is the responsibility of the builder/contractor
to ensure that adequate combustion air has
been provided for the fireplace.
13. Always ensure that the air inlet to the fireplace
is free from debris and any other obstructions
that can block the entrance of air.
14.DO NOT use a fireplace insert or any other
product not specified by the manufacturer of
this LHP appliance for use with this fireplace.
All gas log sets must be operated with the
damper clamped open.
TABLE OF CONTENTS
Safety Rules ......................................Page 2
Tools and Building Supplies ..............Page 2
Precautions .......................................Page 2
Introduction ......................................Page 3
Clearances/Height Requirements ......Page 3
Chimney System ...............................Page 3
Assembly Outline ..............................Page 4
Location of Fireplace .........................Page 4
Assembly Steps ................................Page 5
Preinstallation Notes .........................Page 5
Clearances ........................................Page 5
Installing the Fireplace ......................Page 5
Fireplace and Framing Specifications Page 7
Framing Wall Variations ....................Page 8
Combustion Air Kits ..........................Page 8
Installing the Chimney System ..........Page 9
Ten Foot Rule Summary ....................Page 13
Chimney Component Calculations ....Page 13
Special Offset Instructions ................Page 13
Offset Elevation Chart ........................Page 14
Vertical Elevation Chart ....................Page 15
Offset Calculations ............................Page 16
Installing Offsets ...............................Page 16
30° Offset through Floor/Ceiling .......Page 17
Glass Doors ......................................Page 17
Gas Line Installation ..........................Page 17
Cold Climate Insulation .....................Page 18
Fireplace Finishes ..............................Page 18
Mantels and Trim ..............................Page 18
Hearth Extensions/Wall Shields.........Page 18
Finish Requirements .........................Page 20
Accessories And Components ..........Page 20
PACKAGING LIST:
The assembled wood fireplace is packaged
with:
1 - One envelope containing the literature pack-
age which consists of the homeowner's
manual, installation instructions, warranty
and combustion air cover (located in the
firebox).
2 - One Combustion Air Kit (90L83).
3 - Two Door Sets.
IMPORTANT: PLEASE READ AND
UNDERSTAND THESE RULES TO
FOLLOW FOR SAFETY.
SAFETY RULES:
15. "Smoke free” operation is not warranteed
nor are we responsible for inadequate sys-
tem draft caused by mechanical systems,
general construction conditions, inadequate
chimney heights, adverse wind conditions
and/or unusual environmental factors or
conditions beyond our control.
16. Never, under any circumstances, install
a fireplace, chimney component or any
accessories, that has visible or suspected
physical damage as a result of handling
or transportation. These items should be
inspected by your distributor or qualified fac-
tory representative to ensure safe condition.
When in doubt, consult your distributor.
17. For additional safety considerations and
complete operating instructions, refer to
the Care and Operation Manual provided
with the fireplace.
TOOLS AND BUILDING SUPPLIES
NORMALLY REQUIRED
Tools Supplies
Phillips screwdriver
Hammer
Saw and/or sabersaw
Level
Measuring tape
Plumb line
Electric drill and bits
Pliers
Square
Framing materials
Wall finishing materials
Caulking materials
(noncombustible)
Fireplace surround and
hearth extension
materials
(noncombustible)
WARNING
This fireplace has not been tested
with an unvented gas log set. To
reduce risk of fire or injury, do not
install an unvented gas into
this fireplace.
WARNING
To avoid the risk of damaging
fireplace materials and increas-
ing the risk of fire, do not use the
fireplace to cook or warm food.
PRECAUTIONS
The most important areas of concern dealing
with the installation of factory-built fireplaces
are clearances to combustible materials, proper
assembly of component parts, height of the
chimney system, the proper use of accessories
supplied by the manufacturer and the techniques
employed in using finishing materials applied to
the wall surrounding the fireplace, hearth exten-
sions and wall shields. Each of these topics will
be covered in thorough detail throughout this
manual. Please give each your special attention
as you progress with your installation.
Note: These fireplace systems are not difficult
to install. However, in the interest of safety, it is
recommended that the installer be a qualified or
certified “tradesman” familiar with commonly
accepted fireplace installation and safety tech-
niques as well as prevailing local codes.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
3
Figure 1
TYPICAL INSTALLATION
INTRODUCTION
General Information
The CST38MH Series is a radiant-heat, two-
sided fireplace with standard glass doors and
an outside combustion air kit is provided.
A steel grate is also included to properly posi-
tion the fire and limit the amount of fuel. IF A
REPLACEMENT GRATE IS NEEDED REPLACE
THE GRATE WITH MODEL SGR-38B
ONLY.
Note: Illustrations shown reflect “typical”
installations with nominal dimensions and
are for design and framing reference only.
Actual installations may vary due to individual
design preferences. However, always maintain
minimum clearances to combustible materials
and do not violate any specific installation
requirements.
These fireplaces have been tested and listed
by OMNI Test Labs (Report No. 116-F-20-4) to
U.L. standard 127. These units are intended for
installation in Manufactured Homes, residential
homes and other buildings of conventional
construction including commercial.
These fireplace systems are designed for in-
stallation in accordance with the National Fire
Protection Standard for chimneys, fireplaces
and solid fuel burning appliances; NFPA 211-
latest edition and in accordance with codes
such as the BOCA Basic/National Codes, the
Standard Mechanical Code and the Uniform
Building Codes.
The fireplace opening must be kept a minimum
of 8" (203 mm) from a protected combustible
side wall. A perpendicular side wall can not be
closer that 18" (457 mm). If there is a continu-
ous perpendicular side wall closer than 18" from
the fireplace opening, it must be protected with
a 40" x 40" x 1/2" (1016 mm x 1016 mm x 13
mm) wall shield constructed of a durable non-
combustible material with an equal or greater
insulating value than k=.84 BTU IN/FT2 HR °F
(refer to Pages 18, 19 and 20).
As with all chimney installations, avoid overhead
obstructions such as trees, power lines, etc.
Additionally chimney terminations must meet
certain clearance to roof requirements detailed in
the paragraph titled Ten-Foot Rule Summary.
The fireplace and chimney system must be
enclosed when installed in or passing through
a living area where combustibles or people may
come in contact with it. This is important to pre-
vent possible personal injury or fire hazard.
For questions, please call your distributor or
the manufacturer. Special restrictions apply to
the front and facing of the fireplace and nearby
walls (See Pages 18, 19 and 20).
CHIMNEY SYSTEM
These fireplaces are designed and code listed
for use with Security Chimneys FTF8 chimney
System only. Always use Security Chimneys
FTF8 chimney components with these fireplaces.
Do not modify or alter these components as
this may cause a potential serious hazard and
void the Warranty.
*Construction Materials:
• Framing Materials • Paneling
• Particle Board • Flooring
• Dry Wall • Plywood
• Noncombustible Insulating Materials
• Etc.
Chimney Height
The total height of your Fireplace systems from
the surface the fireplace rests on to the chimney
top must not exceed 80' (24.4m) and must also
meet minimum system height chart.
WARNING
Failure to use manufacture
provided parts, variations in
techniques and construction
materials or practices other than
those described in this manual
may create a fire hazard and void
the limited warranty.
WARNING
Do not pack or fill required air
spaces with insulation or other
material. No material is allowed
in these areas. Secure the
airspace around the chimney
with the firestop/thimble before
completing the installation.
Maintain 2" clearance between
chimney and thimble.
WARNING
If insulation is used, the fireplace
must not be placed directly
against it. Insulation or vapor
barriers, if used, must first be
covered with gypsum board,
plywood, particle board or other
material to assure insulation
and vapor barriers remain in
place.
When complete these fireplace systems con-
sists of four basic “sub-systems”:
1. The Fireplace
2. The Chimney and Termination
3. Glass Doors
4. Combustion Air Kit
CLEARANCES AND HEIGHT
REQUIREMENTS
The fireplace may be placed on or near normal
construction materials*. The combustion air
kit, firestop spacer and roof flashing (not chase
flashings) may be placed directly on or against
normal construction materials.* The chimney
and fireplace outer wrapper require a minimum
2" and 1/2" air space to combustibles respectively.
A combustible mantel may be installed 12" above
the opening of the fireplace as per NFPA 211-
latest edition.
Chimney and
Termination
Firestop
Thimble
Outside Combustion Air Kit
Minimum System Height
Security's FTF8 Pipe
Vertical Installation 15' 0"
One Offsets 16' 0"
Two Offsets 25' 0"
Table 1
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
4
Figure 2
ASSEMBLY OUTLINE
Before You Start
Check your inventory list to be sure you have
all the necessary parts supplied in good us-
able condition. Check also for any concealed
damage.
Check the operation of the damper. The damper
is controlled through the use of a control lever
located within the firebox opening at the top
center just behind the firebox lintel (Figure 3).
The control lever snaps into place at the extreme
range of motion, up and back in the closed
position. When pulled forward and down, the
damper is open.
Figure 3
LOCATION OF FIREPLACE
Carefully select the proper location for heat
circulation, aesthetics, chimney obstructions
and clearance to side wall(s). With proper pre-
planning, a slight adjustment of a few inches
can save considerable time and expense later
during construction and assembly.
Figure 4
Carefully consider the position of the fireplace
opening with respect to the location of adjacent
or nearby stairwells, bath or kitchen exhaust
fans and/or return air registers for forced air
furnaces/air conditioners that could cause a
smoking fireplace condition if the house is
tightly insulated.
When locating the fireplace, consideration must
be given to combustibles and final finishing. For
an example of this, see Figure 5 and confine
the final location of combustible finish materials
to the "Safe Zone".
DO NOT permanently place furniture or other
items such as decorative pillows within 60" of
the fireplace front face.
Figure 5 - Clearances
Wall
Covering
Black Portion Of Frame
Not To Be Covered With
Combustible Materials
Safe
Zone
30°
11-3/8”
18”
Door
Opening
1”
Insulate Joists
Same As Ceiling
Draft Stops
Firestop
CTDT
Termination
Note: Non-
Combustible
Chase
Flashing
Must Be
Used To
Cover
Chase
Opening
Optional
Insulation
In Outside
Walls Of
Chase
8'
Level
Ground Level
Damper
Closed
Damper
Open
Lintel
WARNING
Do not obstruct the collar open-
ings around the base of the chim-
ney at the top of the fireplace.
Do not insulate the chase cavity
with blown or fill type insulation
materials.
Chimney Enclosure
Construct a box-like framed structure to enclose
the fireplace and chimney within the confines
of the manufactured home, not necessarily
above the roof line.
As with all chimney installations, avoid overhead
obstructions such as trees, power lines, etc.
The chimney/fireplace enclosure should be
constructed and insulated just like any outside
wall. In a cold climate, we recommend the base
of the chimney/fireplace enclosure should also
be insulated between the solid continuous floor
beneath the fireplace and the chase bottom.
Insulation in a cold climate installation is not
required for safety.
WARNING
This fireplace and chimney
system is not approved for use
in a bedroom or any room used
for sleeping.
Insulate Joists
Same As Ceiling
Draft Stops
Firestop
CTDT
Termination
Note: Non-
Combustible
Chase
Flashing
Must Be
Used To
Cover
Chase
Opening
Solid
Fireplace
Continuous
Surface
Base
Insulation
(Thermal Barrier)
Note: Local codes may not require firestopping
at the ceiling levels for outside chimney enclo-
sure installations. However, it is recommended
for safety and the reduction of heat loss.
Base Requirements
Front Face
Model Shown
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
5
Figure 7
Figure 6
ASSEMBLY STEPS
Note: The following steps represent the normal
sequence of installation. Each installation is
unique, however, and might require a different
sequence.
1. Position firebox prior to framing or into
prepared framing.
2. Install the chimney system.
3. Install outside combustion air kit.
4. Plumb gas line if a decorative gas appliance
will be used. (Gas connections should only
be performed by an experienced, licensed/
certified tradesman).
5. Install both “All-Glass
TM
” door assemblies.
6. Complete finish wall material, surround and
hearth extension to your individual taste.
7. Inststall the glass doors provided.
Study the three dimensional illustration (Figure
1) to get a general idea of each element of your
fireplace system.
PRE-INSTALLATION NOTES
The fireplace may be installed directly on a
combustible floor or raised on a platform of
an appropriate height. Do not place fireplace on
carpeting, vinyl or other soft floor coverings. It
may, however, be placed on flat wood, plywood,
particle board or other hard surfaces. Be sure
fireplace rests on a solid continuous floor or
platform with appropriate framing for support
and so that no cold air can enter the room from
under the fireplace.
The fireplace may be positioned and then the
framing built around it, or the framing may be
constructed and the fireplace positioned into
the opening.
Usually, no special floor support is needed for
the fireplace, however, to be certain:
1. Estimate the total weight of the fireplace
system including chimney and surround
materials such as brick, stone, etc., to be
installed. Shipping weights for the fireplace
may be found on Page 7.
The firestop thimble supplied with the unit must
be used on a manufactured home installation.
The firestop thimble must extend completely
though the roof cavity to the outermost plane
of the roof (See Figures 21, 22 and 23).
Maintain 1" clearance between the thimble and
the chimney.
If you plan to raise the fireplace and hearth
extension, build the platform assembly then
position fireplace and hearth extension on
top. Secure the platform to the floor to prevent
possible shifting.
CLEARANCES
Minimum clearance to combustibles for the
appliance is as follows: sides - 1/2" (12.5 mm),
floor - 0" (0 mm), adjacent wall - 18" (457 mm),
ceiling - 37-1/2" (953 mm).
Note: Install the hearth extension only as il-
lustrated.
Hearth
Extension
Floor
Hearth
Extension
Metal Safety
Strips
Floor
Hearth
Extension
Floor
Hearth
Extension
Metal Safety
Strips
Platform
CAUTION
Do not block the heat-circulating
air inlet and outlet ports. Doing
so may result in a potential fire
hazard.
CAUTION
The structural integrity of the
manufactured home floor, wall,
ceiling and roof must be main-
tained.
INSTALLING THE FIREPLACE
Step 1. Slide the fireplace into prepared framing
or position fireplace in its final position
and frame later.
The fireplace may not be recessed into a
combustible floor. Maintain the floor to hearth
clearance established by the fireplace lower
front face.
Step 2. Insert the provided metal safety strips,
beneath the fireplace as illustrated
(Figures 6 and 7). The safety strips
should overlap 1/2" for continual
coverage of the floor.
Note: Safety strips are not required when fire-
place rests on a noncombustible surface.
2. Measure the square footage of the floor space
to be occupied by the system, surrounds and
hearth extensions.
3. Note the floor construction, i.e. 2 x 6’s, 2 x
8’s or 2 x 10’s, single or double joists, type
and thickness of floor boards.
4. Use this information and consult your local
building code to determine if you need ad-
ditional support.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
6
The safety strips should extend in front and
sides of the fireplace opening 2" (51 mm) . In
the event a wooden support is used to elevate
the fireplace above the floor, a “Z” type safety
strip should be fabricated and used to protect
the front surface of the wood support as well
as the floor beneath the hearth extension (see
Figures 8 and 9). The safety strips should be
tacked down to prevent possible movement.
Note: The “Z” type safety strip is not sup-
plied.
Step 3. Refer to fireplace drawings and speci-
fications on Pages 7 and 8 for framing
dimensions and details. False header
may be positioned directly on top of
the fireplace spacers (see Figures 10,
11 and 12).
Figure 9
Figure 8
Metal
Safety Strips
2" Min.
(51 mm)
Platform
Metal
Safety Strips
* 2" Min.
(51 mm)
*
*
Figure 10
4 x 6 Header
Spacer
2 x 4 False
Header
Figure 12
Figure 11
No Combustible
Materials in
Shaded Areas
No
Combustible
Materials in
Shaded Areas
If the appliance is to be elevated above floor
level, a solid continuous platform must be
constructed.
The header may rest on the top metal spacers,
but must not be notched to fit around them.
Consult all local codes.
IMPORTANT
Under no circumstances can the
fireplace top spacers (Figure
13) be removed or modified,
nor may you notch the header to
fit around or be installed lower
than the spacers. The header
may be in direct contact with
the top spacers but may not be
supported by them.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
7
Figure 13
7" Min.
(178 mm)
23 ¹⁵⁄₁₆"
(608 mm)
42 ³⁄₄"
(1086 mm)
49"
(1245 mm)
40 ¹⁄₄"
(1022 mm)
4 x 4
Header
2 x 4
False Header
(Optional)
42 ³⁄₄"
(1086 mm)
49"
(1245 mm)
FIREPLACE SPECIFICATIONS
Notes
Due to Lennox' ongoing commitment to quality,
all specifications, ratings and dimensions are
subject to change without notice.
All framing dimensions calculated for 1/2" dry wall
at the fireplace face. If sheathing the chase or
finishing with other thickness materials, calcula-
tions will need to be made.
See Page 8 for Ceiling and Roof Framing
Dimensions
Diagrams & Illustrations Not to Scale
Product Reference Information
Cat.
No.
Model Ship.
Weight
Ship.
Volume
H4629 CST38MH 237 lb. 29.6 cu. ft.
OTL Report No. 116-F-20-4
39-1/4"
(997 mm)
23-15/16"
(608 mm)
25-3/16"
(640 mm)
8"
(203 mm)
Front View
Top View
End View
12-1/2"
"
(318 mm)
48-3/4"
(1238 mm)
8-9/16"
8-13/16"
(217 mm)
3-7/8"
(98 mm)
42-1/2"
(1080 mm)
(224 mm)
Outside (combustion)
Air Inlet
12-1/2"
(318 mm)
48-3/4"
(1238 mm)
10-1/2"
(267 mm)
5-3/4"
(146 mm)
21"
(533 mm)
5-1/4"
(133 mm)
32"
(813 mm)
39-1/4" (997 mm)
38" (965 mm)
End View
Front View
FOAK-6 Outside
Air Kit (provided)
Right Side of
Fireplace
Outside (combustion) Air Kit
Required in Manufactured Home Installations
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
8
Figure 14
FRAMING WALL VARIATIONS
As many as six (6) different framed wall con-
figurations can be constructed to enclose the
Fireplaces. The following illustrations depict
these variations of wall enclosures. Several of
these designs may incorporate book shelves,
wood storage boxes, etc.
Figure 15
Framing Dimensions for Ceiling
Figure 16
CST38MH - Wall Types
“C” Type Wall
“T” Type Wall
“L” Type Wall
“H” Type Wall
“Y” Type Wall
Parallel Wall
A
B
Ceiling Framing
C
D
Roof Framing
Framing Dimensions for Ceiling
Inches (millimeters)
Flue Type A B
FTF8, Vertical
at 2" (51 mm)
16 1/2"
(419 mm)
16 1/2"
(419 mm)
FTF8 Offset 30°
At 2" (51 mm)
16 1/2"
(419 mm)
27"
(686 mm)
Framing Dimensions for Roof
Inches
Pitch
FTF8 at 1" (USA)
C D*
0/12
16 1/2" 16 1/2"
6/12
16 1/2"
19"
12/12
16 1/2"
23 1/2"
* Perpendicular to roof ridge
Step 4. The fireplace should be secured to side
framing members using nailing tabs. Use 8d
nails (Figure 17).
Nailing
Flange
Framing
Stud
Note: The nailing tabs are exempt from the
fireplace clearances described on the fireplace
clearance label.
INSTALL THE COMBUSTION AIR KIT
(required in Manufactured Home installations)
Outside air drawn into the fireplace supplies
air to the fire for combustion. The outside air
kit (FOAK-6, Cat. No. 90L83) must be installed
before the fireplace is framed and enclosed in
the finished walls.
Install the air intake Collar (provided) as shown
in Figure 18.
There is a one-hand operated shut-off valve
located in the enclosed corner of the fireplace
opening behind the screen. Refer to label for
directions of operation. The combustion air
damper should be fully open when the fireplace
is in operation and fully closed when the fire-
place is not in use to prevent outside air from
entering your home.
Connect the 6” (152 mm) Class 0 or Class 1 air
duct to the outside air collar on the appliance
with the tie strip in the outside air kit (provided).
See Figure 18.
Route the Class 0 or Class 1 air duct out the
back or side wall, up through the ceiling or floor
joists to an outside wall. The air duct should be
located above snow level.
Outside combustion air may be run upwards
or vertically through framing and ceiling joists,
with the hood installed through an outside
wall and 3' (914 mm) below the termination.
Ducting may also be run downward through
floor joists and under the home to a ventilated
crawlspace not considered part of the living
area of the home.
Figure 17
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
9
INSTALLING THE CHIMNEY SYSTEM
Step 1. Check flue damper for proper operation.
To open, push handle up and release.
Damper will open automatically. To
close, pull handle down and release
damper will fall to the closed posi-
tion.
Note: The damper may be operated from both
firebox openings.
CAUTION
Allow minimum 2" (51 mm)
chimney air space to combus-
tible framing members through-
out vertical or offset chimney
installation. Also maintain air
space on top of the fireplace
as defined by the spacers and
standoffs.
A minimum 2" (51 mm) air space must be
reserved for all combustible materials extend-
ing for any continuous length surrounding the
chimney.
Reference Figures 15 and 16 on Page 8,
which specify minimum ceiling and roof di-
mensions.
Figure 18 - Outside Combustion Air Kit
Cut or frame a hole through the outside wall for
the installation of the duct inlet hood. A 6 1/2”
(151 mm) diameter hole is sufficient. Feed the
loose end of the flexible air duct through the
hole cut for the inlet hood and attach to collar
on inlet hood using the tie strip provided. Insert
hood into opening. Secure in place with the
No. 8 x 1-1/2” screws provided or with nails
driven through holes in hood flange. Seal with
noncombustible waterproof silicon type caulk-
ing. If additional length of duct is necessary,
purchase locally available Class 0 or Class 1
ducting. The duct may extend up to 50' (15.2
m) in any direction.
Note: Do not terminate combustion air kit in
attic space under any circumstances.
CAUTION
Never locate the air inlet where
it could be blocked by shrubs,
leaves, snow drifts, etc. Never
locate the air inlet in garage or
any area where there is another
fuel burning appliance or prod-
ucts emitting combustible gases
such as paint, gasoline, etc.
In cold climates, it is recom-
mended that the combustion air
duct be insulated.
CAUTION
In no event may the total duct for
bringing in outside air exceed
50' (15.2 m).
Step 2. Using standard construction framing
techniques, construct opening for chim-
ney route up through the ceiling(s) and
roof or through an outside chase.
Framing must maintain adequate mini-
mum air space clearance at all times.
Air Inlet Assembly
(Attach To Floor)
Non-Combustible
Class 0 Or Class 1
6 Inch Air Inlet Duct
Actuator
Arm
Clamp
Securely
At Top And
Bottom
Vented Crawl Space
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
10
For new construction, to determine chimney
center line, use plumb line from roof or ceil-
ing above fireplace to center of flue collar on
fireplace.
For remodeling, plumb to center of flue collar
from ceiling above, drive nail through ceiling
from below to mark position, then mark and
cut to passage from above ceiling (around nail)
(Figure 19). Then plumb from ceiling or roof
level directly above hole which has just been
completed.
Plumb Line
Step 3. Position appropriate thimble/firestop
spacer combination at ceiling and nail
temporarily with two (2) 8d nails or
equivalent fasteners (see Figures 21, 22
and 23). Use thimble/firestop spacer,
model FM8-AT2, if chimney penetrates
ceiling vertically. If chimney penetrates
ceiling at 30˚ angle (offset) chimney use
Model F8FS30-2. Use one fastener on
opposite sides to hold thimble/firestop
spacer combination in position. Nail
permanently, using at least two (2) more
fasteners, after chimney sections have
been assembled through the thimble/
firestop spacer combination and after any
necessary adjustments have been made.
Firestop spacer must be secured by at
least four (4) fasteners when completely
installed.
Note: If there is a room above ceiling level,
firestop spacer must be installed on the bottom
side of the ceiling. If an attic is above ceiling
level, firestop spacer must be installed on top
side of ceiling joist (Figure 20).
Firestop Spacer
F8FS-2
Room Above
Figure 20
Figure 19
Firestop Thimble
FM8-AT2
Attic Above
2”
Clearance
Minimum
Figure 21
Ensure the thimble penetrates the roof opening.
The thimble must extend completely through the
ceiling or roof cavity to the outermost plane of
the roof. Note: Thimble extensions (F8-TE26-2)
are available from your dealer for constructions
in which the distance between the outside of the
roof and the inside of the ceiling exceeds 13".
The thimbles and their extensions provide for
zero clearances to combustibles and must be
used at the ceiling/roof in manufactured homes
(Figures 22 and 23).
Figure 22
Note: Trim Thimble/
Extension To Desired Length
And Pitch At The Rood Line
14" Min.
Pitched Roof
Pitched Roof
Bow Roof
14" Min.
Outer Pipe Of
Chimney
Outer Pipe Of
Chimney
Outer Pipe Of
Chimney
14" Min.
Thimble
FM8-AT2
13"
Thimble
FM8-AT2
Thimble
FM8-AT2
Thimble
Extension
F8-TE26-2
WARNING
Do not allow insulating materials to
be blown into the space inside the
thimble and the chimney. To do so
could result in a fire hazard.
Thimble Cathedral
Ceiling
14" Min.
Outer Pipe Of
Chimney
Use Adjustable Thimble
FM8-AT2 For All Ceiling
Piches, From Flat To
3/12 Pitch.
Figure 23
Step 4. Note: Chimney sections are con-
structed with a unique locking tab
design, which ensures an immediate,
tight assembly between sections. Plan
your chimney requirements carefully
before assembly as chimney is difficult
to disassemble after installation. If
disassembled, the tabs might become
damaged. Be certain tabs are properly
formed to ensure locking tabs engage
properly.
The Security Chimneys FTF8 chimney system
is a two piece chimney, which snap together
from the fireplace up. Start with the inner flue
section with the lanced end up, snap lock it in
to the matching collar on top of the fireplace.
At all subsequent joints, the upper flue section
fits into the preceding flue section. Each piece
snaps together by means of locking tabs (9
locking tabs per joint). Check each piece by
pulling up slightly from the top to ensure proper
engagement before installing the next section.
If the flue has been installed correctly, it will not
separate when you test it. Also, the inner flue
joint where each section is joined should be
tight and flat without gaps (Figure 24).
Figure 24
Outer pipe section installs in just the opposite
way; the lanced end goes down and each new
section goes OVER the outside of the previous
section installed (Figure 25).
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
11
Step 5. The height of vertical chimney pipe sup-
ported only by the fireplace must not
exceed 30'. Chimney heights above 30'
must be supported by a Model FTF8-S4
stabilizer installed at 30' intervals.
Note: The Model FTF8-S4 adds 3" net effective
height to the total chimney system.
Install the Model FTF8-S4 stabilizer by fitting
inner section down into respective section of
proceeding flue pipe and locking outer stabilizer
section into place over the outer chimney pipe.
Position for proper clearance through framed
opening and nail straps securely (under tension
in “shear”) into place on framing. Use 8d nails.
Attach successive lengths of chimney pipe
directly to stabilizer using same techniques as
described in Step 4 (Figure 27).
Locking Tabs
(Lances)
Note: Assemble one component of chimney at
a time (inner section first, then outer section
last) before proceeding with the next complete
section.
Continue to assemble the chimney up through
framed ceiling opening. Assemble just enough
to penetrate the roof flashing openings (Figure
26). Always maintain 2" (51 mm) minimum
air space to combustible materials and always
check each pipe joint (inner and outer) to ensure
proper engagement. Check vertical alignment
of chimney so that it projects from the roof in
true vertical position.
FTF8-S4 Stabilizer
2" (51mm) Min. Air Space
to Combustibles
Figure 26
Step 7. Secure flashing by nailing along the
perimeter into roof using 8d nails or
equivalent fasteners. If shingled roof,
slide upper end and sides of roof flash-
ing under shingles (trim if necessary),
seal the top and both sides of the
flashing to the roof with roof caulking.
Cover fastener heads with roof caulking
(Figure 29).
Figure 28
FTF8 Chimney
FTF8 Flashing
Do Not Seal
Figure 25
Figure 27
Note: Do not apply excessive pressure to any
subsequent chimney sections following the
stabilizer when installing. Ensure each subse-
quent chimney section is securely attached by
testing as noted in Step 4.
Step 6. Select the proper Security Chimneys
roof flashing based on pitch of roof.
Use chart below for selection:
Next, slide roof flashing over extended chimney
section that previously has been installed above
the roof opening in Step 4. Slide flashing all the
way down until the flashing base rests flat on
the roof (Figure 28). Again, check the vertical
position of the chimney and the minimum air
space to combustibles.
Roof Pitch FTF8
Flat to 6/12 F8-F6
6/12 to 12/12 F8-F12
Table 2
Figure 29
Security's chimney sections do not need to be
screwed together. Additional reinforcement is
not necessary except in certain offset conditions
(refer to Page 16, Figure 38).
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
12
Step 8. The standard Security Chimneys FTF8
roof flashing assemblies include a
storm collar. Slide the storm collar over
outer chimney, rest on flashing spacers
and align with top surface of flashing.
Insert tab in slot, pull tight and bend
tab back over slot. Seal storm collar
to outer chimney with roof caulking or
mastic around entire circumference of
pipe. Also add extra roof caulking to the
tab/slot area to seal completely against
water penetration (Figure 30). Check
all joints very carefully to ensure no
water intrusion can take place.
Roof Ridge
120°
CTD
Termination
Chimney
Figure 32
Figure 31
3. Center outer locking section over outer flue
pipe. Push down until locking tabs are firmly
engaged.
4. Pull up slightly on CTD to ensure locking
joint has firmly engaged.
Note: It is recommended that all exterior
exposed metal fireplace components; such as
terminations, flashings, storm collars and/or
flue be painted with a premium quality, high
temperature, rust preventative paint designed
for metal. This is especially important when
installations are made in abnormally adverse
or corrosive environments; such as near lakes,
oceans or in areas with consistently high
humidity conditions. Consult the paint manu-
facturers instructions for proper preparation
and application.
Figure 30
Step 9. FTF locking bands, Model FLB, may
be required if the chimney extends
too high above the roof flashing. As
a general rule, if the chimney extends
more than 6' above the roof flashing,
the use of locking bands is advisable
to strengthen the chimney assembly.
Align the locking band at the chimney
joint. Locking bands wrap around pipe
joints equally covering the joints of both
pipe sections. Use the nut provided and
TIGHTEN snugly. Do not overtighten as
this might damage the chimney section
(refer to Figure 25).
Note: If chimney extends more than 8' (2.4 m)
above roof surface, guy wires are also recom-
mended. Use three (3) guy wires, attach to
locking band assembly, extend and secure to
roof in a triangular pattern (Figure 31). Guy wires
are not supplied by the manufacturer.
Step 10. Using an FTF8-CTD Round Termi-
nation:
1. Hold the CTD over top of last chimney section
(Figure 32).
2. Center inner slip section in inner flue pipe-
slip down.
Mastic
or Roof
Caulking
Locking Band
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
13
Figure 33
TEN FOOT RULE SUMMARY
The minimum chimney height above the roof
and/or to adjacent walls and buildings is speci-
fied by all major building codes.
If the horizontal distance from the peak of
the roof is less then 10' (3 m), the top of the
chimney must be at least 2' (610 mm) above
the peak of the roof.
If the horizontal distance from the chimney
edge to the peak of the roof is more than 10'
(3 m), a chimney height reference point is es-
tablished on the roof surface located horizontally
10' (3 m) from the chimney edge. The top of the
chimney must be at least 2' (610 mm) above
this reference point. In all cases, the chimney
cannot be less then 3' (914 mm) above the roof
at the edge of the chimney.
The 2' in 10' rule is necessary in the interest
of safety, but does not ensure smoke-free op-
eration. Trees, buildings, adjoining roof lines,
adverse wind conditions, etc., may require a
taller chimney should the fireplace not draft
properly (see Figure 33).
Less than
10' (3 m)
10' (3 m)
3' (914 mm)
Min.
2' (610 mm) Min.
3' (914 mm)
Min.
FTF8 CHIMNEY COMPONENT
CALCULATIONS
The minimum installed height of the completed
fireplace system is 15". The maximum system
height is 80' 0".
To determine the number of chimney sections
and chimney components required, follow
these steps:
1. Determine total vertical height of the fireplace
installation. This dimension is the distance
from the surface the fireplace sets on to the
point where smoke exits from the termina-
tion.
2. Determine the number of chimney compo-
nents required, except chimney sections.
This would include thimbles, extensions,
roof flashing, etc.
3. The effective heights of the components
are:
The Fireplace = 48”
FTF8-12 = 10-1/4”
FTF8-18 = 16-1/4”
FTF8-24 = 22-1/4”
FTF8-36 = 34-1/4”
FTF8-48 = 46-1/4”
FTF8-CTD Termination = 6”
4 Determine amoun of chimney height re-
quired by subtracting total combined height
of all pre-selected components (fireplace
and chimney components from total desired
height).
Reference Vertical Elevation Chart and deter-
mine the number of chimney sections (quantity
and length) required. in Table 4 on Page 15.
SPECIAL OFFSET INSTRUCTIONS
To clear any overhead obstructions, you may
offset your chimney system using Security
Chimneys 30° offset and return elbows. Use
two elbows - an offset elbow to initiate the
offset and a return elbow to terminate it. A
30° offset elbow, angling in any direction, may
be the first component used off the top of the
fireplace flue collar. Maintain 2" minimum air
space to combustibles from chimney sections.
See Figures 41 and 42.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
14
A B FTF8-ES30 Number of FTF8 A B
Offset Height Offset/Return FTF8-S4 Chimney Sections Offset Height
(Inches) (Inches) Elbow Set Stabilizer 12" 18" 36" 48" (mm) (mm)
4 15 1 0 0 0 0 0 102 400
9 24 1 0 1 0 0 0 229 622
12 29 1 0 0 1 0 0 305 756
14 33 1 0 2 0 0 0 362 851
17 38 1 0 1 1 0 0 438 978
20 43 1 0 0 2 0 0 514 1111
21 45 1 0 0 0 1 0 533 1149
22 47 1 0 2 1 0 0 565 1207
25 52 1 0 1 2 0 0 641 1334
26 54 1 0 1 0 1 0 667 1378
27 55 1 0 0 0 0 1 686 1416
28 57 1 0 0 3 0 0 718 1467
29 59 1 0 0 1 1 0 743 1505
31 63 1 0 2 0 1 0 794 1600
32 64 1 0 1 0 0 1 819 1638
34 68 1 0 1 1 1 0 870 1734
35 69 1 0 0 1 0 1 895 1772
37 73 1 0 0 2 1 0 946 1861
38 75 1 0 0 0 2 0 972 1905
39 77 1 0 2 1 1 0 997 1956
41 80 1 0 1 4 0 0 1054 2045
43 83 1 0 1 0 2 0 1099 2127
44 85 1 0 0 0 1 1 1124 2165
45 87 1 0 0 3 1 0 1149 2223
46 89 1 0 0 1 2 0 1175 2261
48 91 1 0 2 0 2 0 1226 2324
49 94 1 0 1 0 1 1 1251 2394
50 95 1 0 0 0 0 2 1276 2432
51 97 1 0 1 1 2 0 1302 2483
54 103 1 0 0 2 2 0 1378 2616
55 104 1 0 1 0 0 2 1403 2654
56 106 1 0 2 1 2 0 1435 2705
58 109 1 0 0 1 0 2 1480 2788
62 116 1 1 1 0 3 0 1588 2965
65 122 1 1 0 1 3 0 1664 3099
67 125 1 1 2 0 3 0 1721 3188
69 128 1 1 0 0 1 2 1765 3270
70 130 1 1 1 1 3 0 1797 3321
73 136 1 1 0 2 3 0 1873 3454
75 139 1 1 0 0 0 3 1918 3531
79 146 1 1 1 0 4 0 2026 3715
80 148 1 1 1 0 0 3 2051 3759
82 151 1 1 0 1 4 0 2102 3848
83 153 1 1 0 1 0 3 2121 3886
OFFSET ELEVATION CHART
A
1
C
1
B
1
B
2
C
2
A
2
Figure 35 Figure 36 Figure 37
Figure 34
Stabilizer
A
1
20' Max.
(6m)
B
1
10' Max.
(3m)
A
1
C
1
B
1
B
2
C
2
A
2
FTF8-E30
Return Elbow*
FTF8 Chimney
Sections
FTF8-30
Offset Elbow*
A
B
48"
(1219 mm)
* Part of Offset/Return Package, Model FTF8-ES30.
Table 3
15
11 0 11 1 0 0 0 279 0.28
17 1 5 0 1 0 0 432 0.43
21 1 9 2 0 0 0 540 0.54
27 2 3 1 1 0 0 692 0.69
35 2 11 0 0 1 0 889 0.89
47 3 11 0 0 0 1 1194 1.19
51 4 3 0 1 1 0 1302 1.30
57 4 9 1 0 0 1 1454 1.45
63 5 3 0 1 0 1 1607 1.61
67 5 7 2 0 0 1 1708 1.71
73 6 1 1 1 0 1 1861 1.86
81 6 9 0 0 1 1 2064 2.06
93 7 9 0 0 0 2 2369 2.37
97 8 1 0 1 1 1 2470 2.47
102 8 6 1 0 0 2 2604 2.60
109 9 1 0 1 0 2 2775 2.78
113 9 5 2 0 0 2 2883 2.88
119 9 11 1 1 0 2 3035 3.04
127 10 7 0 0 1 2 3232 3.23
137 11 5 1 0 1 2 3493 3.49
139 11 7 0 0 0 3 3537 3.54
143 11 11 0 1 1 2 3645 3.65
149 12 5 1 0 0 3 3797 3.80
155 12 11 0 1 0 3 3950 3.95
159 13 3 2 0 0 3 4058 4.06
165 13 9 1 1 0 3 4210 4.21
173 14 5 0 0 1 3 4407 4.41
183 15 3 1 0 1 3 4667 4.67
185 15 5 0 0 0 4 4712 4.71
189 15 9 0 1 1 3 4820 4.82
195 16 3 1 0 0 4 4972 4.97
201 16 9 0 1 0 4 5124 5.12
206 17 2 2 0 0 4 5232 5.23
212 17 8 1 1 0 4 5385 5.39
219 18 3 0 0 1 4 5582 5.58
230 19 2 1 0 1 4 5842 5.84
231 19 3 0 0 0 5 5886 5.89
236 19 8 0 1 1 4 5994 5.99
242 20 2 1 0 0 5 6147 6.15
248 20 8 0 1 0 5 6299 6.30
Height Of Number Of FTF8 Height Of
Chimney Only Chimney Lengths Chimney Only
Inches Feet/Inches 12" 18" 36" 48" MM M
Height Of Number Of FTF8 Height Of
Chimney Only Chimney Lengths Chimney Only
Inches Feet/Inches 12" 18" 36" 48" MM M
252 21 0 2 0 0 5 6401 6.40
258 21 6 1 1 0 5 6553 6.55
266 22 2 0 0 1 5 6756 6.76
276 23 0 1 0 1 5 7010 7.01
278 23 2 0 0 0 6 7061 7.06
282 23 6 0 1 1 5 7163 7.16
288 24 0 1 0 0 6 7315 7.32
294 24 6 0 1 0 6 7487 7.49
298 24 10 2 0 0 6 7576 7.58
304 25 4 1 1 0 6 7728 7.73
312 26 0 0 0 1 6 7925 7.93
322 26 10 1 0 1 6 8185 8.19
324 27 0 0 0 0 7 8230 8.23
328 27 4 0 1 1 6 8338 8.34
334 27 10 1 0 0 7 8490 8.49
340 28 4 0 1 0 7 8642 8.64
344 28 8 2 0 0 7 8750 8.75
350 29 2 1 1 0 7 8903 8.90
358 29 10 0 0 1 7 9100 9.10
368 30 8 1 0 1 7 9360 9.36
370 30 10 0 0 0 8 9404 9.40
374 31 2 0 1 1 7 9512 9.51
380 31 8 1 0 0 8 9665 9.67
386 32 2 0 1 0 8 9817 9.82
390 32 6 2 0 0 8 9925 9.93
396 33 0 1 1 0 8 10077 10.08
404 33 8 0 0 1 8 10274 10.27
414 34 6 1 0 1 8 10535 10.53
416 34 8 0 0 0 9 10579 10.58
420 35 0 0 1 1 8 10687 10.69
426 35 6 1 0 0 9 10839 10.84
432 36 0 0 1 0 9 10992 10.99
437 36 5 2 0 0 9 11100 11.10
443 36 11 1 1 0 9 11252 11.25
450 37 6 0 0 1 9 11449 11.45
461 38 5 1 0 1 9 11709 11.71
462 38 6 0 0 0 10 11754 11.75
466 38 10 0 1 1 9 11855 11.86
472 39 4 1 0 0 10 12008 12.01
478 39 10 0 1 0 10 12160 12.16
FTF8 VERTICAL ELEVATION CHART
Table 4
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
16
OFFSET ELBOW ASSEMBLY
Offset elbows install the same as chimney
sections. First, snap the inner section INTO
the preceding inner section of flue. Check con-
nection by pulling up slightly to ensure a tight
fit. Next, the outer sections snap locks OVER
the preceding outer section of chimney. Again,
check outer section by pulling up slightly to
ensure proper connection is made.
RETURN ELBOW ASSEMBLY
Return elbows install the same way as round
terminations and stabilizers:
Step 1. Hold return elbow over top of last
chimney section.
Step 2. Center inner slip section into inner flue
pipe-slip down.
Step 3. Center outer locking section over outer
chimney pipe-push down until locking
joint has firmly engaged.
Step 4. Pull up slightly on return elbow to
ensure locking joint has firmly en-
gaged.
Step 5. Secure support straps to framing
members by nailing under tension in
sheer (Figure 40).
The offset and return elbows may be attached
together, or a section or sections of chimney
may be used between, but do not exceed 20'
(6.1 m) in total length between elbows (Figure
35). If sections of pipe exceed 10' (3 m) between
elbows, a chimney stabilizer must be used at
the midpoint. The stabilizer support straps
must be attached under tension (in shear) to
structural framing members above. When two
sets of offset elbows are used, the maximum
combined length of chimney used between
elbows cannot exceed 20' (6.1 m) (Figures 35
through 37). Example: If C
1
= 10' (3m) then
C
2
cannot exceed 10' (3 m).
If an offset exceeds 6' in length, each chimney
joint beyond the first 6' of offset to the return
elbow, must be secured by a No. 8 x 1/2" sheet
mental screw located at the underside of the
joint (Figure 38).
Maximum offset of the chimney system is 30°.
Two offset elbows must not be assembled to
form a 60° offset. However, two sets of offset
and return elbows may be used on a single flue
system, provided the total height of the system
exceeds 25' (7.6 m).
Return elbow support straps must be securely
attached under tension (in shear) to structural
framing members above.
OFFSET CALCULATIONS
1. Use Offset Chart to determine amount of
horizontal offset (A) and height (B) for various
chimney sections.
2. Use “Height of Chimney Only” column to
determine combinations of pipe used above
return elbow to achieve desired heights. Ref-
erence Components Effective Height Chart in
Figure elevation chart section.
3. Use Elevation Chart as job estimator only.
Add necessary firestop spacers and stabilizers
as required. Firestop spacers must be used as
shown in Figures 20 and 21 and stabilizers as
shown in Figure 27.
INSTALLING OFFSETS
First, review Offset Elevation Chart (Table 3)
and Figure 34 on Page 14.
Step 1. Determine the offset distance where
chimney is to pass through the first ceiling-
dimension “A.” To find this point on your
ceiling, first determine the center point for a
vertical chimney following the instructions for
vertical installation.
Measure height to the ceiling from the top of
fireplace-dimension “B.” Use Offset Elevation
Chart to find dimension “A.” Mark point where
you will drive your nail to show the center point
for your offset ceiling cut.
Step 2. Proceed by using the Straight Up In-
stallation Instructions for cutting and framing
ceiling and roof openings.
Note: See “Framing and Dimension” Chart for
the sizes of the ceiling and roof openings. The
size of the roof opening varies with the degree
of pitch of the roof.
Chimney
Section
Joints
No. 8 x ¹⁄₂" SMS
Screws Required at
Ever
y Joint Past 6'
No Screws Required in
Joints for First 6' of Offset
4'
6'
Underside of Chimney
Return Elbow
Figure 38
Figure 39
A 1/8" (3 mm) diameter hole must be drilled in
the chimney joint using a 1/8" (3 mm) diameter
drill. Hole should be drilled in center of joint
overlap (Figure 39). Be sure to drill only through
the outer chimney casting. Do not puncture
the inner flue.
Figure 40
Note: The return elbow assembly performs the
same function as a stabilizer. Consider this when
determining the need for a stabilizer.
Note: Do not apply excessive pressure to any
subsequent chimney section following return
elbow assembly when installing. Ensure subse-
quent chimney sections are securely attached
by testing as noted above.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
17
CHIMNEY OFFSET 30° THROUGH FLOOR
OR CEILING
It may be necessary to assemble the chimney
at 30° when passing through the floor or ceil-
ing area. Use the F8FS30-2 firestop spacer as
shown in Figures 41 and 42.
Support the chimney at floor or ceiling penetra-
tion with a FTF8 stabilizer if distance of chimney
below ceiling is 10' (3 m) or more. Maintain 2"
(51 mm) minimum air space to combustibles
from chimney sections. The chimney must
pass vertically through the attic space.
F8FS30-2
Firestop
Spacer
FTF8-S4
Stabilizer
2" (51mm)
Min. Air
Space
2" (51mm)
Min. Air
Space
30
°
Firestop
and Attic Above
10'
(3m) Max.
Attic Space
2" (51mm)
Min. Air
Space
30° Firestop
and Room Above
10'
(3m) Max.
Room Above
2" (51 mm)
Min. Air
Space
F8FS30-2
Firestop
Spacer
FTF8-S4
Stabilizer
CAUTION
If an optional brass or stainless
door was purchased, remove the
plastic protective coating from
the doors before assembly and
installation. Failure to remove
the coating before first use will
result in damage to the finish.
CAUTION
Do not touch the doors with your
hands while the fireplace is in
use. Always use door handles.
Doors will become very hot when
fireplace is in use.
WARNING
These fireplaces should be oper-
ated only with the doors fully
closed (Figure 44).
GAS LINE INSTALLATION
The Fireplaces have been approved to accept
a 1/2" (13 mm) gas line for an approved gas
appliance. Always have the appliance installed
by a qualified, licensed plumber in accordance
with all local building codes. The gas line may
enter either end of the fireplace.
CAUTION
Plumbing connections should
only be performed by a quali-
fied, licensed plumber. Main
gas supply must be off when
plumbing gas line to fireplace
or performing service.
Figure 41
Figure 42
GLASS DOORS
The Fireplaces require the use of the standard
glass doors (provided). The use of any other
non-listed door on these fireplaces may result
in a potential fire hazard and is not recom-
mended.
Figure 44
Figure 43
Pivot Pin
Roller
Pin
Upper Door
Guide Track
Spring Clip
Make a careful inspection of all parts before
installing the doors to ensure they are undam-
aged and complete. There will be two (2) glass
door assemblies for both sides of the CST38MH
fireplace.
Note:
• Design characteristics of a dual-opening
fireplace (whether masonry or factory-built)
may cause it to not draft properly and smoke.
For this reason, glass doors are required with
model CST38MH fireplaces.
• Upper door pivot pins can also be loosened
for adjustment purposes; however, it is easier
to loosen lower pins.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
18
If you’re installing a gas line, connect it before
the fireplace is framed and enclosed in the
finished wall. The gas knockout is determined
by a 1-1/8" (29 mm) round indentation located
at the bottom and slightly off center in the
side refractories. THE KNOCKOUT IS ALWAYS
REMOVED FROM INSIDE THE FIREPLACE. DO
NOT REMOVE THE KNOCKOUT UNLESS YOU
ARE INSTALLING A GAS LINE. If removal is at-
tempted from the outer wrapper, side-refractory
damage may occur. With a medium-sized ham-
mer, lightly tap the surface of the indentation.
The refractory material is very thin in this area
and is easily removed. Once a small hole has
been made, continue tapping until you have
reached sufficient diameter for the gas line to
fit through. The entire knockout does not have
to be removed. Remove insulation in the gas
line channel.
Install a 1/2" (13 mm) gas supply line through
fireplace wall for connection to a decorative
gas appliance inside the firebox. Outside, the
gas supply line must connect to a gas shut-off
valve usually recessed flush into the wall or floor.
The valve should be controlled by a removable
valve key for safety.
Always plumb gas line installation per local
codes. Check all connections using a gas leak
test solution (also referred to as bubble leak
solution). Note: Using a soapy water solution
(50% dish soap, 50% water) is an effective
leak test solution but it is not recommended,
because the soap residue that is left on the
pipes/fittings can result in corrosion over time.
Never test any gas line connection with a match
or open flame.
Hearth Extensions and Wall Shields
A hearth extension must be installed with all
fireplaces. Its purpose is twofold. It protects a
combustible floor in front of the fireplace from
both radiant heat and sparks and it distinguishes
the prescribed hearth extension area from other
non-protected surfaces.
The hearth extension must extend beyond
the front and both sides of the fireplace side
openings. Use a hearth extension constructed
of a durable noncombustible material having
an equal or better (lower k value) insulating
value of k = .84 BTU IN/FT
2
HR °F or a thermal
resistance that equals or exceeds r=1.19 HR
°F FT
2
/BTU IN. A minimum 3/8" (10 mm) thick
noncombustible material is all that is required
over a noncombustible or slab floor.
If there is a continuous perpendicular side
wall closer than 18" (mm) from the fireplace
opening, it must be protected with a 40" x 40"
x 1/2" (1016 mmx 1016 mm x 13 mm) wall
shield (see Figure 46) constructed of a durable,
noncombustible material having an equal or
better (lower k value) insulating value than k =
.84 BTU IN/FT
2
HR °F. A continuous protected
side wall can not be closer than 8" (203 mm)
from the fireplace opening.
Secure the hearth extension to the floor to
prevent possible shifting.
12"
(305 mm)
Min.
6"
(152 mm)
Finished Wall
Spacer
Combustible
Mantel
and Trim
12"
(305 mm)
Max.
False
Header
Typical U.S. Installation
1 ¹⁄₂"
(38 mm)
Fireplace Opening
CAUTION
When using the decorative gas
appliance, the fireplace damper
must be set in the fully open
position.
For all areas, this provision is intended only
for connection to a decorative gas appliance
incorporating an automatic shut-off device and
complying with the standard for Decorative Gas
Appliances for installation in vented fireplaces,
ANSI Z21.60. Install in accordance with the
National Fuel Gas Code, ANSI Z223.1.
IMPORTANT
Repack insulation material in
square hole around gas line,
interior and exterior, to seal.
Figure 45 - Mantel Clearances
COLD CLIMATE INSULATION
If you live in a cold climate, it is especially
important to seal all cracks around the fire-
place and wherever cold air could enter the
room with noncombustible material. Surround
material must be caulked where it meets the
black metal facing of the fireplace to avoid
cold air intrusion. Use noncombustible caulk-
ing material only on fireplace facing to seal.
Also, the outside air inlet duct should be
wrapped with noncombustible insulation to
minimize the formation of condensation. Do
not place insulation materials directly against
the chimney sections.
Note: 2" (51 mm) air space must be preserved
for all materials extending for any continuous
length adjacent to the chimney.
It is especially important to insulate between
the studs of an outside chase cavity and under
the floor if the floor is above ground level. Do
not place insulation directly against the fireplace
or chimney system.
FIREPLACE FINISHES
Mantels and Trim
It is sometimes best to frame your fireplace af-
ter it is positioned and the chimney is installed.
Frame enclosure for chimney and fireplace with
2 x 4’s (or heavier) lumber.
Note: The header may rest on the two (2) metal
top spacers on top of the unit but the header must
not be notched to fit around the spacers.
In all installations, combustible mantels and
trim may be installed 12" (305mm) above the
opening as per NFPA 211-latest edition. and
Figure 45. If a mantel is of a noncombustible
material, it is exempt from the requirements as
long as it does not interfere with the operation
of glass doors.
19
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Figure 46
Hearth Extension Dimensions
A 16"
B 28-1/2"
C 8"
D 44-1/2"
Methods of Determining Hearth Extension and Wall Shield
Equivalents - To determine the thickness required for the alternate
material when either the "k" value or "r" value is known, use either the
k formula or r formula.
Example: If Micore 160 is to be used for the hearth extension fireplace,
how thick must this material be?
k
M
= k value per inch of alternate material
r
M
= r value per inch of alternate material
T
M
= minimum thickness required for alternate material
T
S
= standard thickness of the alternate material
k
L
= k value per inch of listed material
r
L
= r value per inch of listed material
T
L
= minimum thickness of listed material
Note: An asterix "*" indicates, it is a value taken from Table 5.
Using the k formula:
Minimum k-value (per Inch) of Specified min.
thickness of = alternate material (k
M
) x thickness
alternate k-value (per inch) of listed
material (T
M
) of listed material (k
L
) material (T
L
)
T
M
(inches) = kM x T
L
*.84
T
M
(inches) = *.35 x 1"
*.84
.416 (inches)= .416 x 1"
Answer - The minimum required thickness of the Micore 160 is .417," there-
fore round up to nearest standard thickness available which is 1/2."
Minimum r-value (per Inch) Specified min.
thickness of = of listed material x thickness
alternate r-value (per inch) of listed
material of alternate material material
T
M
(inches) =
r
L x T
L
r
M
T
M
(inches) = *1.19 x 1"
* 2.86
.417 (inches)= .416 x 1"
Answer - The minimum required thickness of the Micore 160 is .417," there-
fore round up to nearest standard thickness available which is 1/2."
Using the r formula:
Note: To convert inches to millimeters divide by .03937.
Listed Material
k (per inch) r (per inch) Listed Min.Thickness
Listed Material .84
K
L
1.19
r
L
1"
T
L
** Approved Alternate Materials for Floor/Hearth Protection
AlternativeMaterials Thermal Values MinimumThickness
(rounded to nearest 1/8 inch)
k (per inch)
K
M
r (per inch)
r
M
Min. Thickness
T
M
Kaowool M Board .47 2.13 .56" (1/2")
Micore 160™
U.S. Gypsum
.35 2.86 .42" (3/8")
Micore 300™
U.S. Gypsum
.46 2.17 .55" (1/2")
Durock™ Cement Board
U.S. Gypsum
1.92 .52 2.29" (2-1/4")
Hardibacker™ 1.95 .513 2.32" (2-3/8")
Hardibacker 500™ 2.30 .435 2.74" (2-3/4")
Cultered Stone Hearth-
stone™
2.82 .355 3.36" (3-3/8")
Wonderboard 3.23 .31 3.85" (3-7/8")
Super Firetemp M
Johns-Manville
.61 1.64 .73" (3/4")
Super Firetemp L
Johns-Manville
.54 1.85 .64" (5/8")
Face brick 9.00 .111 10.71" (10-3/4")
Common brick 5.00 .20 5.95" (6")
Cement mortar 5.00 .20 5.95" (6")
Ceramic tile 12.5 .08 14.88" (14-7/8")
Marble ~11 ~.09 13.10" (13-1/8")
Table 5
** If the hearth extension material(s) that is intended to be used is NOT listed
on Table 5, the material can still be used if the material(s) is noncombustible.
However, the manufacturer of the material must provide either the listed k-value
per inch or r-value per inch with listed thickness so that the minimum thickness
required for the hearth can be calculated (per instructions on this Page and/or
as specified in the NFI Certification manuals).
Note: Also see NFI (National Fireplace Institute) Certification Manuals showing
other exceptable caluculation methods and acceptable alternate materials
which can be used.
B
A
C
C
Protected
Side Wall
Model CST-38
D
40"
40"
A
B
D
C
C
Wall Shield Required
Where Less Than 18".
Adjacent Wall is Never
Allowed Closer
Than 8".
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
20
ACCESSORY PARTS AND COMPONENTS
LIST FOR MODEL CST38MH
The accessory parts and components shown on
Pages 21 and 22 are to be used only with your
CST-38MH fireplace system. Separate installa-
tion instructions are packaged with all combus-
tion air kits and chimney terminations.
If you encounter any problems or have ques-
tions concerning the installation or application
of this system, please contact your distributor.
For the name of your nearest distributor, please
call 1-800-953-6669.
LHP
1110 West Taft Avenue
Orange, CA 92865
Figure 48
Maximum Thickness of Hearth Extension
when Fireplace is on the Floor.
5 ⁵⁄₈"
*
(143 mm)
Max.
*
5 ¹⁄₈" (130 mm)
If “C” Style Door
Is Used.
Figure 47
8" (203 mm)
11 ³⁄₈"
(289 mm)
30˚
Combustible
Materials Allowed
in Shaded Area
1" (25 mm)
Minimum Distance
to Protected Side Wall
4 ⁵⁄₈"
(118 mm)
18"
(457 mm)
Minimum Distance
to Unprotected Side Wall
Model CST-38
FINISH TO YOUR TASTE
There are a wide variety of “finished looks”
for your Fireplace from formal wall decor with
elaborate mantels to rustic wood paneling or
warm brick facings.
Calculating Minimum Thickness if
Multiple Materials are Used
At times it is important to know what
combination of materials are acceptable for use
as floor protection. The “R values” are used to
determine acceptable combinations of materials
because “R values” are additive where r and k
values are not.
“R value” = 1/k = "r" x thickness of material
used
Example: Given that the required “R value”
for a suitable floor protector used must be
equal to or greater than:
“R” = r
L
x T
L
= 1.19 x 1” = 1.19."
If it is desired to elevate a marble hearth
extension to a level of 5” or more above
the floor surface. What combination of
noncombustible materials can be used to
accomplish this?
If common brick is used so that the 3-1/2”
dimension is the height, “R” for the common
brick becomes:
brick
“R”
M
= r
M
x T
S
= 0.20 x 3-1/2" = .70
Using 1/2” of mortar to set the brick, “R” for
the mortar is calculated as follows:
mortar
“R”
M
= r
M
x T
S
= 0.20 x 1/2" = .10
Next, a 3/4" marble slab set in 1/2" mortar cov-
ers the brick, “R” for the marble and mortar
becomes:
marble
“R”
M
= r
M
x T
S
= 0.05 x 3/4" = .038
mortar
“R”
M
= r
M
x T
S
= 0.20 x 1/2" = .10
The sum of all “R values” is: .70 + .10 +. 038
+ .10 = .938
This would NOT be an acceptable combination
of material for the hearth extension since the
total calculated “R value” of the materials used
is under the required “R value” of 1.19. An
additional layer of insulating materials must
be used.
Note: Also see NFI Certification Manuals for
expanded explanation on calculating “R val-
ues” when multiple materials are used.
WARNING
The crack between the fireplace
and the hearth extension must be
sealed with a noncombustible
material.
WARNING
When installing hearth extension
in front of a non-circulating fire-
place model, the fireplace must be
raised if height of hearth extension
exceeds 5-3/4" above the bottom of
fireplace (Figure 47).
When installing the hearth exten-
sion be careful not to block the
heat-circulating air inlet grill on
circulating models.
Only noncombustible materials like marble,
stone, tile, brick, etc. may overlap the black
front facing, but be careful not to interfere
with the operation of the glass doors. Seal
all joints between the black facing and wall
surrounds to prevent cold air intrusion. Use
noncombustible caulking material only to seal
the black metal facing to the surround material
on the finished wall.
Combustibles may also project beyond the
sides of the fireplace opening as long as they
are kept within the shaded areas, as illustrated
in Figure 48.
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